Networks conforming to IEEE 1394 are made up, as shown in FIG. 1, of a number of nodes K1 . . . through Kn in the network, the theoretical maximum number of which is limited to 63 by the length of the corresponding node identifier (ID). The node ID for addressing the individual nodes has a length of 6 bits; the address 0xFF is reserved as a broadcast address. If it is desired to connect more than 63 nodes, the possibility exists of connecting multiple separate buses B1, B2 via a network bridge (bus bridge) NB. These buses can in turn be individually addressed via a bus ID. The bus ID has a length of 10 bits, corresponding to 1,024 buses. Theoretically, therefore, 1,024*63=64,512 nodes can be connected into one network system.
A serial bus conforming to IEEE 1394 supports the transfer of asynchronous and isochronous data. Whereas the reception of asynchronous data packets must be acknowledged by the receiving node in order to ensure reliable data transfer, no acknowledgment is necessary for isochronous data. Network bridges for coupling multiple buses must support the transfer of both data types. At the same time, they must ensure that in more-complex topologies each data packet can reach its receiver, and that all the buses connected into the network system run on a synchronized cycle. Draft Standard IEEE 1394.1 specifies the functionality of such a High Performance Serial Bus Bridge, specifically for use in networks conforming to IEEE 1394 b.